The Pencil Urchin (Phyllacanthus parvispinus) is a temperate/sub tropical sea urchin species that belongs to the family Cidaridae. It is also commonly referred to as the Eastern slate pencil urchin and can be found on the east coast of Australia from Point Cartwright in Queensland to Bass Strait in Tasmania. This species can be commonly found in cracks and crevices on inshore rocky reefs from depths of 0 to 80 metres. During the daytime it wedges it locks itself into crevices with its thick spines and hence is able to tolerate strong wave action in the inter tidal zone. This species is known to feed on algae and encrusting organisms from sea floor debris.
The Pencil Urchin (Phyllacanthus parvispinus) has a maximum body diameter (known as test) of 9 cm and the primary spines grow to 7cm.